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(11)

EP 4 128 694 A1

(12)

(43) Date of publication: 08.02.2023 Bulletin 2023/06 (21) Application number: 21715271.9 (22) Date of filing: 30.03.2021

(51) International Patent Classification (IPC):  H04L 29/06(1990.01) G06F 17/18(1995.01) G06F 21/50(2013.01) G06F 21/56(2013.01) (52) Cooperative Patent Classification (CPC): H04L 63/145; H04L 63/1433; G06F 21/564 (86) International application number: PCT/EP2021/058360 (87) International publication number: WO 2021/198295 (07.10.2021 Gazette 2021/40)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA ME Designated Validation States: KH MA MD TN (30) Priority: 03.04.2020 EP 20168112 (71) Applicant: British Telecommunications public limited company London E1 8EE (GB)	(72) Inventors: WANG, Xiao-Si London EC4V 5BT (GB) WELDING, Jessica London EC4V 5BT (GB) (74) Representative: British Telecommunications public limited company Intellectual Property Department  9th Floor One Braham Braham Street London E1 8EE London E1 8EE (GB)